Cosmic Observatory
From Accct Wiki
The Comet Observatory is one of the many areas from Super Mario Galaxy for the Wii. It acts as the 'hub' area, similar to Peach's Castle from Super Mario 64.
It is accessed through the Gateway Galaxy and is where Princess Rosalina is found. Much like Peach's Castle in Super Mario 64, or Delfino Plaza in Super Mario Sunshine, certain parts of the observatory are unlocked as Mario acquires Grand Stars. This is because the Grand Stars are used to power a large beacon in the middle of the observatory. Once five Grand Stars are acquired, the observatory will have enough power to travel toward the center of the universe.
There are many Domes scattered throughout the Observatory. The Domes are used to access the Galaxies. Galaxies are accessed by getting more Power Stars to unlock more Domes. Additional Galaxies can be unlocked by feeding Hungry Lumas that appear. The Domes are the Terrace, the Fountain, the Kitchen, the Bedroom, the Engine Room, and the Garden. According to the Lumas, the Domes are used to view the cosmos.
It is Confirmed as A Place for the Main Transmorphers Website
And when Brawl Was Released, It Crashed on Smash City